JPS63167458A - Rotary head type digital signal reproducing device - Google Patents

Abstract

PURPOSE:To make a capstan, a pinch roller, and a capstan motor, etc., unnecessary and to simplify a mechanism, by providing a reel motor which controls the revolution of the reel of a magnetic tape corresponding to a tracking error signal. CONSTITUTION:The frame address and the block address values of a data outputted from a RAM23 and a written data are supplied to a CPU27, and a difference between the addresses is calculated, and the CPU27 controls a driver 28 corresponding to a calculated difference, and when the difference of the addresses exceeds a constant value, it decreases the speed of the reel motor 16 at a constant ratio, and adversely, when a data amount in the RAM23 is reduced less than a prescribed level, it increases the speed of the reel motor 16 at the constant ratio. Also, when the data amount in the RAM23 is kept at an appropriate value, the CPU27 functions as a tracking circuit, and the speed of the reel motor 16 can be controlled at a stationary value.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a rotary head type digital signal playback system for playing back digitally recorded audio signals, such as R-DAT and 8mm video tape recorders. Regarding equipment.

[Summary of the invention]

In this invention, a digital signal recorded on a tilted track of a magnetic tape is reproduced by a rotary head, and the tracking state of the rotary head with respect to the tilted track is controlled by a reel motor.

[Conventional technology]

In R-DAT, P is placed on the inclined track of the magnetic tape.
CM audio data is recorded and played back.

When recording or reproducing audio signals, the magnetic tape generally needs to run at an accurate speed, so the magnetic tape is driven by a capstan and a pinch roller, and the rotation of the capstan is controlled in response to a tracking error signal. .

On the other hand, in the case of high-speed search for the start of a subcode signal, for example, the magnetic tape is run at a speed that is, for example, 200 times faster than normal recording and reproduction. Since it is difficult to achieve such high speeds with capstans and pinch rollers, in such cases the magnetic tape is run by rotating its reel at high speed. For this reason, the reel stand is driven by a capstan motor that rotates the capstan via a belt, gears, etc., or a reel motor that drives the reel stand is provided separately from the capstan motor.

[Problem that the invention seeks to solve]

In this way, conventional equipment uses pinch rollers, capstans,
It requires a capstan motor, a reel motor, etc., and has the disadvantage that the mechanism is complicated and expensive. Furthermore, devices that drive the reel stand with a capstan motor without a reel motor not only require a larger capstan motor due to high-speed feed, but also require gears, clutches, etc. that can be switched between normal running and high-speed running. there were.

[Means for solving problems]

The present invention relates to a rotary head type digital signal reproducing device, which includes: a rotary head for reproducing digital signals recorded on inclined tracks on a magnetic tape; a D/A converter that converts the signal whose error has been corrected by the correction circuit into a D/A converter; a tracking circuit that generates a tracking error signal from the signal output from the rotating head; and a tracking error signal. and a reel motor that controls the rotation of the reel of the magnetic tape in response to the rotation of the reel of the magnetic tape.

[Effect]

The reel motor runs the magnetic tape at a normal recording and reproducing speed. A rotating head reproduces the digital signal recorded on the inclined track, and the reproduced signal is temporarily stored in memory. The correction circuit corrects errors in the signal stored in the memory and outputs the corrected signal to the D/A converter. D/
The A converter performs D/A conversion on the input signal and outputs it. The tracking circuit generates a tracking error signal from the reproduction signal output by the rotary head. The reel motor is controlled in response to the tracking error signal.

〔Example〕

An example in which an embodiment of the present invention is applied to an R-DAT will be described below.

R-DAT has 19 pieces of data recorded in one track.
It consists of 6 blocks, of which the PCM data section consists of 128 blocks.

Furthermore, each PCM block is assigned a block address, making it possible to identify the 128 blocks in one track. Also, in this PCM section, frame addresses are assigned once every two blocks, with two adjacent tracks with different azimuth angles as one unit, and there are 16 types of addresses from 0 to 15. Attached.

Addresses are sequentially attached with a period of 16 frames, that is, one period of 32 tracks.

The following explanation will be given assuming the R-DAT format as described above.

In FIG. 2, the magnetic tape 1 is running in the direction of the arrow in the figure at the same speed as during recording. This magnetic tape 1
Recording tracks Ta and Tb having azimuth angles a and b, respectively, are alternately formed on the top.

In this example, the rotary head drum is rotated at twice the number of revolutions during recording, and head scanning trajectory 2 shown in Figure 2 is the scanning trajectory of head HA with azimuth angle A of the two rotating heads. be. Although the scanning locus of the head HB with the azimuth angle B is not shown, it is located in the middle of the scanning locus 2 of the head HA with the azimuth angle A. In other words, if the number of rotations is doubled, the scanning pitch of the head in the longitudinal direction of the tape will be 172, which is the same as when recording, and if the number of rotations is multiplied by n, the pitch will be 1/n. Recognize.

At this time, since the head HA and the azimuth are the same track portion, the reproducible portion of the head HA is the shaded portion in FIG. A head HA with the same azimuth passes through all parts. However, if we focus on one track Ta, the head HA passes through it three times, that is, the drum rotates three times, and the track T
a is completely regenerated. In this case, the reproduction order is X→y-*z in the figure, which does not match the recording order.

However, as mentioned above, one track of digital data is divided into multiple blocks and has a frame address and a block address added to it, so the playback signal is written to the memory block by block according to these addresses and arranged in the order of frame and block address. It can be changed.

Therefore, even if the scanning inclination angle of the head is different from the inclination angle of the recording track as shown in FIG. 2, digital signal reproduction can be performed in the same way as when the two are correctly aligned.

At this time, if there is duplicated data, it can be detected and ignored using the block address and frame address.

Furthermore, if there is a portion of each track that cannot be reproduced because the head does not pass through it, the rotational speed of the drum may be increased.

Furthermore, in order to improve the reliability of reproduction, it is also possible to select a good reproduction signal by increasing the number of rotations of the drum and intentionally reading data in duplicate.

The relationship between the head HB and the track Tb is also the same, and even if there is a track shift, it is possible to completely reproduce one track.

FIG. 1 is a block diagram of an example of the apparatus of this invention.

The tape 1 is fed out from the supply reel 11 and placed on the drum 1.
1 winding -
15.

Heads HA and HB are arranged on the drum 12 with a distance of 180' from each other, and are rotated by a driver 19 in the direction of the arrow in the figure at twice the number of rotations during recording.

Digital signals reproduced by the rotary heads HA and HB are supplied to a demodulation circuit 22 via a reproduction process circuit 21 consisting of an RF amplifier, an equalizer, and a PLL, and are demodulated. The demodulated data is written to a predetermined location in the memory (RAM) 23 according to the frame address and block address, and returned to the original order. The data returned to the original order and read out from the RAM 23 is subjected to error correction, deinterleaving, etc. in the signal processing unit 24.
The signal is converted into the original analog audio signal through the D/A converter 25 and low-pass filter 26.

By the way, in this reproducing device, data is read from the RAM 23 at a constant speed in synchronization with the timing of a clock pulse having crystal precision.

On the other hand, data is written into the RAM 23 at a speed that corresponds to the playback tape speed; the faster the tape speed is, the faster the write input speed is, and the slower the tape speed is, the slower the write speed is. Therefore, it is necessary to keep the tape speed approximately constant so that the capacity of the RAM 23 does not overflow or become empty.

The example in FIG. 1 takes this point into consideration. In FIG. 1, the amount of data currently stored in the RAM 23 is
This can be approximately determined from the difference between the frame address and block address of the data output from M23 and the frame address and block address of the data written to RAM 23 at that time.

Therefore, these address values are sent to the CPU 2 from the RAM 23.
7 and calculate the difference between the above addresses. and,
The driver 28 is controlled by the CPU 27 in accordance with this calculated difference.
The reel motor 16 is controlled by the output of this driver 28 to control the tape speed.

For example, when the difference in the addresses becomes larger than a certain value, that is, when the amount of data in the RAM 23 increases, the speed of the reel motor 16 is reduced by a certain percentage,
Conversely, when the amount of data in the RAM 23 falls below a certain level, the speed of the reel motor 16 is increased by a certain percentage.

In this way, the RAM 23 will not overflow or become empty.

When the amount of data in the RAM 23 is at an appropriate value, tape feeding control is performed such that the speed of the reel motor 16 also reaches a steady value.

That is, in this case, the CPU 27 functions as a tracking circuit that generates a tracking error signal. The rotation of the reel motor 16 is transmitted to the take-up reel stand 14 via gears 17 and 18, and the magnetic tape 1 is controlled at substantially the same speed as during normal recording and reproduction.

By doing so, the audio signal can be reproduced even if the tracking circuit originally provided in the R-DAT is omitted.

In the above, the traveling speed of the rotary head is made faster than that during recording so that one inclined track is scanned multiple times. However, similar operations can also be achieved with different configurations.

For example, a magnetic tape is wound 180 degrees around a drum with a diameter of 15 na equipped with one double gap (+-azimuth) head, and the tape is wound at 4000 rpm [! One turn.

Considering the case where information is recorded by passing a recording current alternately through the double gap, the recording pattern formed in this case is that the magnetic tape is wound 90 degrees around a drum with a diameter of 30 strokes equipped with two heads, and the magnetic tape is recorded at 2000 ppm. It will be the same as if it were rotated. Therefore, when playing this magnetic tape by winding it 90 degrees around a drum having a diameter of 30 nm and having two heads mounted thereon, the number of revolutions should be set to 400 rpm. Further, if the drum has a diameter of 30 nwa and is wound at 90 degrees and has four reproducing heads (A1→B□→A2→B2), the rotational speed may be 2000 rpm.

Although one inclined track is traced multiple times in the above example, a tracking error signal may be generated from the ATF signal using the original tracking circuit, and the reel motor 16 may be controlled via the driver 28. . In this case, the rotating drum 12 (rotating head HA
, HB) is the same speed as normal recording and playback (for example, 20
The magnetic tape 1 is also run at approximately the same speed as during normal recording and reproduction. At this time, it is difficult to achieve tracking control equivalent to that achieved using capstans and pinch rollers, but what is recorded on the magnetic tape 1 is a digital signal, so even if an error occurs, it is difficult to achieve tracking control. Correct reproduction of the audio signal is possible because the signal processing section 24, which functions as a correction circuit, can perform correction.

When running the magnetic tape 1 at a high speed (for example, 200 times the speed) when performing a high-speed search for a subcode signal, it is sufficient to simply increase the rotational speed of the reel motor 16.

If the gear 18 is rotated and connected to the supply reel stand 13,
It is clear that the magnetic tape 1 can be run in the opposite direction at normal speed or at high speed.

〔Effect of the invention〕

As described above, the present invention provides a rotary head type digital signal reproducing device including: a rotary head for reproducing digital signals recorded on inclined tracks on a magnetic tape; a memory for storing signals output from the rotary head; a correction circuit that corrects errors in the signal that has been corrected; a D/A converter that converts the signal whose error has been corrected by the correction circuit into a D/A converter; and a tracking circuit that generates a tracking error signal from the signal output from the rotary head. Since it is equipped with a reel motor that controls the rotation of the magnetic tape reel in response to a tracking error signal, a capstan, pinch roller, capstan motor, etc. can be omitted, simplifying the configuration and reducing cost. − can be made cheaper. Therefore, it is particularly suitable as a reproduction-only device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a rotary digital signal reproducing device of the present invention, and FIG. 2 is a diagram for explaining its operation. 1... Magnetic tape 2... Scanning locus 11... Supply reel 12... Rotating drum 13... Supply reel stand 14... Take-up reel stand 15... Take-up reel 16... Reel motor 17, 18...Gear 19...Driver 21...Reproduction process circuit 22...Demodulation circuit 23...RAM 24...Signal processing section 25...D/A converter 26...・Low pass filter 27...CPU 28...Driver or higher

Claims (1)

[Claims] A rotary head for reproducing digital signals recorded on inclined tracks on a magnetic tape, a memory for storing signals output from the rotary head, a correction circuit for correcting errors in the signals stored in the memory; a D/A converter that performs D/A conversion of the signal whose error has been corrected by the correction circuit;
A rotary head type digital device comprising: a tracking circuit that generates a tracking error signal from a signal output from the rotary head; and a reel motor that controls rotation of a reel of the magnetic tape in response to the tracking error signal. Signal regenerator.